The mother of the two men suspected of carrying out the Boston Marathon bombing says her younger son would have faithfully obeyed his older brother, a devout Muslim who investigators now fear may have become radicalized.

The older brother, Tamerlan Tsarnaev, 26, had become an increasingly pius Muslim in recent years, partly at the urging of his mother, she said.

The younger son, Dzhokhar Tsarnaev, 19, was a sophomore at UMass-Dartmouth where he had a reputation for partying and drugs.

The mother, Zubeidat Tsarnaeva, described Tamerlan as "a person of strong will," a "leader" who could influence people.

Tamerlan's influence was perhaps felt most by his younger brother Dzhokhar.

"They loved each other. What Tamerlan was said was law for Dzhokhar. That's how I raised them. What the elder brother says, the younger brother has to do. That is according to Islam," the mother told ABC News in a phone call today.

"We were all very connected. My boys were very close to me, and especially Tamerlan," she said.

She and Tamerlan spoke almost daily, and when they both lived in the United States he would visit every weekend. The last time they spoke it was during the suspects' tense standoff with police, during which Tamerlan was killed and his younger brother Dzhokhar was badly wounded, but captured alive.

Tamerlan told her what was happening and as she began to cry and scream the line went dead. She frantically searched for the television remote control. Sometime later, her daughter called to say Tamerlan had been killed.

Tsarnaeva refused to believe her sons could have committed acts of terror. She accused the U.S. government of framing the brothers because they were afraid of Tamerlan.

"They wanted to eliminate Tamerlan and Dzhokhar was just nearby because he was driving him to the university," she said. She also denied that they owned or possessed any guns.

The mother also seemed to endorse conspiracy theories that the U.S. government was behind the September 11, 2001 attacks, suggesting the same people killed her sons.

Tsarnaeva said she urged Tamerlan to embrace Islam in 2008, concerned about his drinking, smoking, and pursuit of girls. She said he began to read more about it on the internet. The mother said she also urged him to quit boxing because she told him Islam prohibits hitting someone in the face.

Tsarnaeva praised Tamerlan's wife, an American-born woman named Katherine Russell who converted to Islam and began to wear a headscarf.

"She is a serious, good, American girl who converted to Islam as if she had always been a Muslim. We all love her a lot," she said. The two had a daughter who is now a toddler.

Russell chose the name Karima after converting to Islam, the mother said. She said her son approved, telling his wife, "If you like it, it's a good name."

In 2011, the FBI investigated Tamerlan at the behest of an undisclosed foreign government, which feared he was planning to travel there to link up with militant groups. The bureau said in a statement on Friday that their investigation yielded nothing of concern.

The mother said that since Friday's standoff with police, law enforcement agents have visited family members in the United States and confiscated cell phones and computers.

Dzhokhar, meanwhile, was described as less religious. His mother said they had high hopes for him because he was a good student with a scholarship. She said he had a big heart, describing how he and Tamerlan cried when their cat got sick.